1. Field of the Invention
The present invention relates to an aqueous colored fine particle dispersion comprising an oil-soluble dye, an ink comprising the colored fine particle dispersion, and an ink-jet recording method using the ink.
2. Description of the Related Art
In recent years, with the spread of computers, ink-jet printers have widely been used to print images on paper, films, cloth or the like not only in offices but also at home. As ink-jet recording inks, oily inks, aqueous inks, and solid inks are known. Of these inks, aqueous inks are advantageous and are the main current from the standpoints of ease of production, handling performance, odor, safety and the like.
Since many types of aqueous inks use water-soluble dye which is dissolved in a molecular state, the inks are high in clearness and color density. However, the inks have the following drawbacks: (1) since the dye is water-soluble, the water resistance thereof is poor, whereby, at the time of printing images on the so-called plain paper with the ink, bleeding is generated to deteriorate print quality remarkably; (2) the light fastness of the inks is poor; and (3) the storability of images resulting from the inks is remarkably poor due to the effect of an oxidizing gas (such as SOx, NOx, or ozone) in recording paper in which an ink-receiving layer containing porous inorganic fine particles is formed on its surface (hereinafter, sometimes referred to as “photographic image-quality paper”).
Thus, aqueous inks using pigment or disperse dye have been suggested to solve the above-mentioned problems (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 56-157468). Although the water resistance of these aqueous inks is improved to some degree, it cannot be said to be sufficient. The pigment or disperse dye dispersed in the aqueous inks is lacking in storage stability so as to cause such a problem that clogging occurs easily in nozzles for jetting the inks. Furthermore, the inks using the pigment or dye do not infiltrate photographic image-quality paper sufficiently, so as to cause a problem in that when the paper is rubbed with fingers, the pigment or the dye peels off easily from the surface thereof.
Methods of encompassing an oil-soluble dye in a polymer have been suggested (see, for example, JP-A Nos. 58-45272 and 62-241901). However, the inks obtained by the methods have insufficient color tone, color reproducibility and image durability against, in particular, oxidizing gas or the like. When images are printed on photographic image-quality paper with the inks, the abrasion resistance thereof is insufficient. Inks having excellent coloring forming property and abrasion resistance due to the introduction of a salt-forming group and a polyalkylene oxide group into a polymer have been suggested (see, for example, JP-A No. 2001-123097). The inks have a good resistance against rubbing by fingers, but do not have a high-level abrasion resistance, such as a resistance against rubbing with an eraser. Methods of using a high-boiling-point organic solvent and a dye in ink to improve the color tone or abrasion resistance of images resulting from the ink have been suggested (see, for example, JP-A No. 2001-262018). However, the exhibited properties are insufficient in cases where high-level the image durability is required.
As described above, under the present circumstances, the following colored fine particle dispersion has not yet been provided: a colored fine particle dispersion which has good handling performance, low odor-generating properties and high safety, which has dispersed particles of a small particle size, and which is excellent in dispersion stability and storage stability, this colored fine particle dispersion therefore being capable of producing the following advantages when the dispersion is applied to ink: the ink causes no clogging in the tips of nozzles to exhibit good jetting stability; the ink is good in color forming ability and color tones (hue) without depending upon kinds of paper; the ink is good in ink permeability even when the ink is used for the photographic image-quality paper; after the ink is used to print images, the images exhibit good water resistance, and in particular, good image storability and abrasion resistance; and the ink makes high-density and high-quality printing possible.
The invention overcomes the above-mentioned problems in the prior art and can attain the following objects.
One object of the invention is to provide a colored fine particle dispersion which has good handling performance, low odor-generating properties and high safety; which is suitable for aqueous ink for writing, aqueous ink for printing and ink for information-recording; which has dispersed perticles of a small particle size; and which is excellent in dispersion stability and storage stability.
Another object of the invention is to provide an ink-jet recording ink which is suitable for thermal piezoelectric, electric field, and acoustic ink-jet methods; which has good handling performance, low odor-generating properties and high safety; which has dispersed particles of a small particle size; which is excellent in dispersion stability and storage stability so as to decrease the generation of clogging in the tips of nozzles; which has no dependency upon kinds of paper so as to exhibit excellent color forming property and color tones when the ink is used to print images on paper selected at will; which is excellent in inkpermeability into photographic image-quality paper; which gives good water resistance, and in particular, good image storability and abrasion resistance to images printed with the ink; and which makes high-density and high-quality recording possible.
Still another object of the invention is to provide an ink-jet recording method which has good handling performance, low odor-generating property and high safety; which overcomes defectivejetting due to clogging of the tips of nozzles; which has no dependency upon kinds of paper so as to exhibit excellent color forming properties and color tones when the ink is used to print images on paper selected at will; which is excellent in ink permeability into photographic image-quality paper; which gives good water resistance, and in particular, good image storability and abrasion resistance to images printed with the ink; and which makes high-density and high-quality recording possible.